Profile

Yoshihiro Kawahara (川原圭博) is an Associate Professor in the department of Information and Communication Engineering, The University of Tokyo.His research interests are in the areas of Computer Networks and Ubiquitous and Mobile Computing. He is currently interested in developing energetically autonomous information communication devices. Even though wireless communication technology advances, the terminals are still tethered by power codes. He's trying to eliminate the power codes by the Energy Harvesting and the Wireless Power transmission. He's not only interested in academic research activities but also enjoyed designing new business and its field trial while joining IT startup companies.

He received his Ph.D. in Information Communication Engineering in 2005, M.E. in 2002, and B.E. in 2000. He joined the faculty in 2005. He is a member of IEICE, IPSJ, and IEEE. He's a committee member of IEEE MTT TC-24 (RFID Technologies.) He was a visiting assistant professor at Georgia Institute of Technology and MIT Media Lab.

Lecture

Fundamental Exercise on
Programming

Experiments and Exercises on
Electrical, Electronic, and Information and Communication (Spring and Fall)

Research Projects (Selected)

Instant Inkjet Circuits

Instant Inkjet Circuit is a low cost, fast and accessible technology to support the rapid prototyping of functional electronic
devices. It is able to print highly conductive traces and patterns
onto rigid or flexible substrates such as paper and plastic films
cheaply and quickly. In addition to providing an alternative to
breadboarding and conventional printed circuits, we demon-
strate how this technique readily supports large area sensors
and high frequency applications such as antennas. Unlike existing methods for printing conductive patterns, conductivity
emerges within a few seconds without the need for special
equipment. We demonstrate that this technique is feasible
using commodity inkjet printers and commercially available
ink, for an initial investment of less than US$100. We believe that this technology will be of immediate appeal to researchers in the ubiquitous computing domain, since it supports the fabrication of a variety of functional electronic device prototypes.

Energy Harvesting From ambient RF signals

In order to sense the world around us, realization of a low-cost and maintenance-free wireless sensor network system is crucial. For commercial mass production of sensing systems, all-round cost cutting methods are required. In this paper, we propose a near-perpetual networked sensing platform, which scavenges electromagnetic power from ambient Radio Frequency (RF) signals using a dipole antenna printed on a paper surface. Our ultimate goal is to realize thin and fluffy wireless sensor nodes that can be carried by the wind and cover large areas like fluttery petals of blossom. This work is conducted with very close collaboration with Georgia Institute of Technology granted by NEDO.

Multi-hop Wireless Power Transmission

We work on a new concept of routing electric power by wireless transfer on two-dimensional surfaces, such as floors and walls. Unlike any other existing wireless power transfer scheme, this method can deliver electric power over a wide range with minimum loss. We realize this method by using a magnetic antenna array. Each array element can be selectively resonated with adjacent elements to deliver power without physical contact.

Mobile phones and wearable sensing technologies

Almost all recent mobile phones are equipped with multiple sensors, such as cameras, GPS, and accelerometers. By exploiting the sensing features, we capture many different events and share them over the mobile network. We have developed a robust and light-weight activity recognition method using on mobile phone accelerometer, and demonstrated E-Coaching Sports wear concept as well as a calorie meter. We also focus on reduction of the battery consumption of the mobile device using compressed sensing technology, development of large scale corpus.